1. Field of the Invention
The present invention relates to an optical fiber bundle which is used, for example, in a light guide provided in an endoscope, an optical fiber sensor, etc., and a method of manufacturing the optical fiber bundle.
2. Description of the Related Art
In general, in a main body of an endoscope, an operation section is coupled to a proximal end portion of an elongated insertion section that is to be inserted into the human body. An image guide and a light guide for illuminating an object of observation are inserted in the insertion section. Further, one end portion of a flexible tube, such as a light guide cable, is connected to the operation section. The light guide is extended from within the insertion section to the flexible tube side. The other end portion of the flexible tube is connected to an external light source. Illumination light from the external light source is supplied to the light guide, and the object of observation is illuminated.
In the meantime, in order to enhance the functionality of the endoscope, there is a demand for separation between the operation section of the endoscope and the flexible tube such as a light guide cable. In this case, the operation section of the endoscope is provided with a flexible tube connection section to which the flexible tube is detachably attached. Further, the flexible tube is provided with an endoscope connection section. The endoscope connection section of the flexible tube is detachably attached to the flexible tube connection section of the operation section.
As described above, in the case where the operation section of the endoscope is separated from the flexible tube such as a light guide cable, it is necessary, in the prior art, to cut a single light guide, which extends from within the insertion section to the flexible tube side, and to separate the single light guide into a light guide on the insertion section side and a light guide on the flexible tube side. In addition, at the connection part between the flexible tube connection section of the operation section and the endoscope connection section of the flexible tube, the end face of the light guide on the flexible tube side and the end face of the light guide on the endoscope body side are configured to be optically coupled. By this structure, illumination light, which is guided from the light guide on the flexible tube side, is transmitted to the light guide on the endoscope body side so that the object of observation may be illuminated, and the functionality of the endoscope is secured.
Besides, the optical fiber bundle that constitutes the light guide is conventionally manufactured by the following method. Specifically, end portions of a plurality of optical fibers are bundled with use of a glass tube, and these end portions are fused. Thereby, the end face of the light guide connection section is formed (see, e.g. Jpn. Pat. Appln. KOKAI Publication No. 6-347645). The optical fiber bundles that are manufactured in this manner are assembled in the state in which the optical fiber bundles are inserted in the insertion section and the flexible tube.
When the insertion section of the endoscope body and the flexible tube are connected, the end face of the light guide of the flexible tube is optically coupled to the end face of the light guide of the endoscope body. Thereby, illumination light from the external light source is guided from the optical fiber bundle of the light guide on the flexible tube side to the optical fiber bundle of the light guide on the insertion section side, and the illumination light is radiated on the object of observation.